1. Field of the Invention
This invention relates to a metering device for cameras, and more particularly, to a metering device in which the aggravation of photo-responsive characteristic attributable to the capacity present in the light-sensing element has been corrected.
2. Description of the Prior Art
A metering device for cameras is well-known in which a photodiode is connected between the positive and the negative input terminals of an operational amplifier and a logarithmic conversion diode is connected between the negative input terminal and the output terminal of the operational amplifier so that an exposure meter may be controlled by the output of the operational amplifier.
However, the presence of the capacity in the photodiode causes an electric charge to be stored in the capacity when some noise enters the device, and a potential difference is thus created between the positive and the negative input terminals of the operational amplifier thereby sharply to drop the output potential of the operational amplifier. Unfortunately, a relatively long time is required before such charge stored in the capacity is exhausted by natural discharge and during that time, the output potential of the operational amplifier remains low and the operational amplifier becomes irresponsive to the light which enters the photodiode. This has led to aggravation of the photoresponsive characteristic of the metering device.